At a laboratory developing new plants, Alice (Emily Beecham) and Chris (Ben Whishaw) create a species with a scent designed to induce happiness; Alice names it Little Joe after her son. Then several incidents make the divorcée wonder whether contact with the flower might have subtle but very serious side effects.

Everything about Hausner's movie - the inventive script, the crisp, fluid camerawork, the use of Teiji Ito's haunting music and the carefully nuanced performances - is a model of expressive precision, exhibiting an astute grasp of the psychological and social dynamics of the workplace, family, parenthood and gender relations. Crucially, Hausner maintains a satisfying ambiguity as to why characters behave as they do and what that might mean, producing a philosophically intriguing, consistently compelling cinematic enigma. 

these plants represent the proliferation of antidepressants among a new social order that would prefer to numb itself to feeling in the name of the alleged comfort that comes with conformist passivity. Think about how that idea plays into what’s happening in the world right now — and suddenly, Little Joe feels like it’s a movie made for these times.
Peter Travers Rolling Stone

It presents a landscape of medicated zombies who join in a cult of their own well-being, and who regard their new state as an ideology
Owen Glieberman Variety